The Siemens 6ES7391-1AA00-0AA0 is a spare-part connector for the 24 V supply rail on S7-300 CPUs and the FM352-5 module, sold in packs of 10 units. It belongs to the SIMATIC S7-300 family. This is a consumable accessory — the small plastic connector that snaps onto the front of the CPU or FM352-5 to bring in the 24 VDC loop power. If you've lost one, cracked it during a swap, or need spares for a panel build, this is the exact Siemens order code.
Lifecycle reality — eol_hot
For a BOM line that still carries this code, the procurement path is the surplus and independent-distribution channel. Do not assume it will be on the shelf at a standard distributor.